"When the landline rings at that hour, normally it is because someone died," he said.

"I'm still a little overwhelmed."

He added: "I stand on the shoulders of giants. This is a very humbling award."

Image:The winners were announced during a news conference in Stockholm

Juleen Zierath of the Nobel Academy said the winners had raised "awareness of the importance of a proper sleep hygiene".

The Nobel Assembly said: "The paradigm-shifting discoveries by the laureates established key mechanisms for the biological clock.

"Our wellbeing is affected when there is a temporary mismatch between our external environment and this internal biological clock, for example when we travel across several time zones and experience jet lag.